﻿using System;
using System.Collections.Generic;

/// <summary>
/// 1. 模式的结构
/// 享元模式的主要角色有如下。 
/// 抽象享元角色（Flyweight）:是所有的具体享元类的基类，为具体享元规范需要实现的公共接口，非享元的外部状态以参数的形式通过方法传入。
/// 具体享元（Concrete Flyweight）角色：实现抽象享元角色中所规定的接口。
/// 非享元（Unsharable Flyweight)角色：是不可以共享的外部状态，它以参数的形式注入具体享元的相关方法中。
/// 享元工厂（Flyweight Factory）角色：负责创建和管理享元角色。当客户对象请求一个享元对象时，享元工厂检査系统中是否存在符合要求的享元对象，如果存在则提供给客户；如果不存在的话，则创建一个新的享元对象。
/// </summary>
namespace Flyweight
{
    class Program
    {
        static void Main(string[] args)
        {
            FlyweightFactory factory = new FlyweightFactory();
            Flyweight f01 = factory.getFlyweight("a");
            Flyweight f02 = factory.getFlyweight("a");
            Flyweight f03 = factory.getFlyweight("a");
            Flyweight f11 = factory.getFlyweight("b");
            Flyweight f12 = factory.getFlyweight("b");
            f01.operation(new UnsharedConcreteFlyweight("第1次调用a。"));
            f02.operation(new UnsharedConcreteFlyweight("第2次调用a。"));
            f03.operation(new UnsharedConcreteFlyweight("第3次调用a。"));
            f11.operation(new UnsharedConcreteFlyweight("第1次调用b。"));
            f12.operation(new UnsharedConcreteFlyweight("第2次调用b。"));
        }
    }

    //非享元角色
    public class UnsharedConcreteFlyweight
    {
        private String info;
        public UnsharedConcreteFlyweight(String info)
        {
            this.info = info;
        }
        public String getInfo()
        {
            return info;
        }
        public void setInfo(String info)
        {
            this.info = info;
        }
    }
    //抽象享元角色
    interface Flyweight
    {
        public void operation(UnsharedConcreteFlyweight state);
    }
    //具体享元角色
    class ConcreteFlyweight : Flyweight
    {
        private String key;

        public ConcreteFlyweight(String key)
        {
            this.key = key;
            Console.WriteLine("具体享元" + key + "被创建！");
        }
        public void operation(UnsharedConcreteFlyweight outState)
        {
            Console.WriteLine("具体享元" + key + "被调用，");
            Console.WriteLine("非享元信息是:" + outState.getInfo());
        }
    }
    //享元工厂角色
    class FlyweightFactory
    {
        private Dictionary<String, Flyweight> flyweights = new Dictionary<String, Flyweight>();
        public Flyweight getFlyweight(String key)
        {
            Flyweight flyweight = null;
            if (flyweights.ContainsKey(key))
            {
                Console.WriteLine("具体享元" + key + "已经存在，被成功获取！");
                flyweight = flyweights[key];
            }
            else
            {
                flyweight = new ConcreteFlyweight(key);
                flyweights.Add(key, flyweight);
            }
            return flyweight;
        }
    }
}
